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Xkoto Chief Technology Officer Ariff Kassam explained that the Database Load Balancer works by way of having each node maintain an exact replica of the database. To do that, any write transactions have to be broadcast to all nodes. The technology performs load balancings on read transactions, spreading reads across the cluster to get the speed up.
"Thats how we get scale upby parsing and distributing reads across the cluster," Kassam said. "We dont reach everybody with reads. We just send to" the node with the most capacity at a given time, he said.

According to Lee, Xkotos technology is achieving 85 percent scalability each time a low-end, commodity server is added to a cluster, as the company demonstrated in a benchmark performed at IBMs request.

That compares to adding boxes to a cluster without a load balancer, wherein the database cant use the added box unless an enterprise is using software from a vendor, such as IBMs DPF (Data Partitioning Facility).
The typical cluster setup involves two nodes with software that enables failover. Oracle has its Data Guard software, while Sybase has Replication Server, each of which enables two-node replication.
One node serves up application requests, while the other node sits idle, waiting until failover occurs. But such passive waiting doesnt increase performance; its only there in case of a disaster scenario.
The differentiator with Xkotos technology is its "active-active" status, Lee said. "Every node in the cluster is actively serving transactions all the time," he said. "Its not sitting there for the once in a blue moon when the primary node fails."
When Savvicas MySQL server crashed, the company realized MySQL wouldnt be able to grow with it, Lee said, and that Savvica would have to go with a more heavy-duty, commercial database. Because the company had already decided it would need a commercial database sometime down the line, it didnt bother to explore the options for MySQL clusters, he said.
Those solutions include Continuent, which was named Emic Networks until October. Continuent offers clustering for MySQL databases, as well as Apache Web servers and PostgreSQL, SQL Server, Oracle and Sybase databases.
MySQL, for its part, introduced clustering capabilities in April 2004, with the company bragging about MySQL Cluster delivering five 9sin other words, 99.999 percentavailability in testing.
The issue with Oracle Database 10g grid technology was cost, Lee said.
To use Oracle in a grid configuration, companies must use RAC (Real Application Clusters), starting with at least Standard Edition 1, which costs $15,000 per CPU.
"Right out of the gate, its not an option for a startup," Lee said. "They want as close to zero spend as possible."
DB2 Express-C fit the bill, with its price of zero.
Xkoto intends to supply database load-balancing technology for other commercial databases as well, with a Sybase release slated for the third quarter of this year. A SQL Server version is scheduled for the end of 2006 or early 2007. The company has also fielded requests to port to Oracle and is evaluating whether to do it this year or next, Lee said.
In a release scheduled for April or May, IBM AIX will be supported.
The current release supports Red Hat and SUSE Linux.
Database Load Balancer is priced per cluster, at $10,000 for companies with 5,000 and fewer employees and $40,000 for larger companies.
Editors Note: This story was updated to correct information about Xkotos marketing.Check out eWEEK.coms for the latest database news, reviews and analysis.

Lisa Vaas is News Editor/Operations for eWEEK.com and also serves as editor of the Database topic center. Since 1995, she has also been a Webcast news show anchorperson and a reporter covering the IT industry. She has focused on customer relationship management technology, IT salaries and careers, effects of the H1-B visa on the technology workforce, wireless technology, security, and, most recently, databases and the technologies that touch upon them. Her articles have appeared in eWEEK's print edition, on eWEEK.com, and in the startup IT magazine PC Connection. Prior to becoming a journalist, Vaas experienced an array of eye-opening careers, including driving a cab in Boston, photographing cranky babies in shopping malls, selling cameras, typography and computer training. She stopped a hair short of finishing an M.A. in English at the University of Massachusetts in Boston. She earned a B.S. in Communications from Emerson College. She runs two open-mic reading series in Boston and currently keeps bees in her home in Mashpee, Mass.